A Microfluidic Experiment on CO 2 Injection for Enhanced Oil Recovery in a Shale Oil Reservoir with High Temperature and Pressure

Zhengdong Lei (), Yishan Liu, Rui Wang, Lei Li, Yuqi Liu and Yuanqing Zhang
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Zhengdong Lei: Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China
Yishan Liu: Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China
Rui Wang: Exploration and Development Research Institute of Daqing Oilfield, Daqing 163412, China
Lei Li: College of Petroleum Engineering, China University of Petroleum, Qingdao 266580, China
Yuqi Liu: Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China
Yuanqing Zhang: Exploration and Development Research Institute of Daqing Oilfield, Daqing 163412, China

Energies, 2022, vol. 15, issue 24, 1-15

Abstract: In recent years, CO 2 huff and puff has become one of the most important methods developed for unconventional shale oil reservoirs and has been widely used in all major shale oil fields. However, the microscopic mechanism of CO 2 contacting with crude oil is complex, and the change law of the residual oil occurrence after CO 2 injection is unclear. In this paper, a micro visualization fluid flow simulation experiment (microfluidic experiment) under high temperatures and high pressure of a shale reservoir was conducted to reveal the micro mechanism of CO 2 and crude oil after contact at the microscale. This allows conclusion of more precise results than any experiment conducted in a room environment. Combined with gas–oil two-phase micro flow characteristics, the production mechanisms of crude oil by CO 2 huff and puff at the pore scale are clarified, and the change characteristics of the remaining oil occurrence state after CO 2 injection are quantified. The results show that CO 2 mainly produces crude oil in macropores and microfractures in the injection stage of huff and puff, improves the mobility of crude oil through diffusion dissolution in the soaking stage, and that the driving of dissolved gas is dominant in depressurization production. The major micro-mechanisms for CO 2 to improve shale oil are extraction and dissolution expansion, accompanied by a variety of secondary mechanisms, such as the miscibility effect, oil expansion, viscosity reduction and other contact effects, as well as the improvement of crude oil properties. The simulation results of huff and puff development show that soaking is an important stage to enhance oil recovery. With increasing soaking time or the soaking pressure, the recovery degree of crude oil will increase positively.

Keywords: microfluidic experiment production mechanism; CO 2 huff and puff; shale oil (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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